The Protein Kinase B/Akt enzymes are a group of serine/threonine kinases that are overexpressed in certain human tumors. International Patent Application Publication Number WO 2008/006040 and U.S. Pat. No. 8,063,050 discuss a number of inhibitors of AKT, including the compound (S)-2-(4-chlorophenyl)-1-(4-((5R,7R)-7-hydroxy-5-methyl-6,7-dihydro-5H-cyclopenta[d]pyrimidin-4-yl)piperazin-1-yl)-3-(isopropylamino)propan-1-one (GDC-0068), which is being investigated in clinical trials for the treatment of various cancers. The free base and dihydrochloride salt form of GDC-0068 isolated in Example 14 of U.S. Pat. No. 8,063,050 are hygroscopic and difficult to develop into a solid dosage form. What is needed are forms and formulations of GDC-0068 and its salts that have improved pharmaceutical properties.